| 摘要 |
A phantom assembly adapted to simulate a human subject to verify the accuracy of a carbon monoxide diffusing capacity (DLco) measuring device for testing the functional integrity of the subject's alveolar-capillary membrane. The device includes a mouthpiece through which the subject inhales a mixture of carbon monoxide and an inert gas in a predetermined ratio. Then after a breath holding interval the subject exhales into the mouthpiece an alveolar sample whose carbon monoxide content is analyzed by the device to evaluate the subject's condition. The assembly includes a phantom whose chamber is interposable between the mouthpiece of the DLco device and a calibration syringe having a known capacity. Within the chamber cavity is a flow tube that extends between valved mouthpiece and syringe ports on opposing end wall of the chamber. The valved port arrangements are such that when the syringe is operated in its negative pressure mode, the flow tube is then blocked and the cavity is unblocked, this blocking action being reversed when the syringe is operated in its positive pressure mode. Injected into the cavity is a given amount of inert gas whereby when the syringe is operated in its negative pressure mode, a known amount of the gas mixture is drawn from the device into the cavity where it is intermingled with the inert gas therein, thereby reducing the ratio of carbon monoxide to the inert gas to a predetermined degree to produce a test sample that fills the syringe. And when the syringe is thereafter operated in its positive pressure mode, the test sample is then expelled from the syringe and fed through the tube to the DLco device. Should the device be malfunctioning, its analysis of the sample will yield readings that deviate from the correct values, thereby indicating that the device is inaccurate.
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